Given the equation: $3x - y = 21$ What is the $x$ -intercept?
Explanation: The $x$ -intercept is the point where the line crosses the $x$ -axis. This happens when $y$ is zero. Set $y$ to zero and solve for $x$ $3x - 0 = 21$ $3x = 21$ $(\dfrac{1}{3}) \cdot (3x) = (\dfrac{1}{3}) \cdot (21)$ $x = 7$ This line intersects the $x$ -axis at $(7, 0)$. ${1}$ ${2}$ ${3}$ ${4}$ ${5}$ ${6}$ ${7}$ ${8}$ ${9}$ ${10}$ ${\llap{-}2}$ ${\llap{-}3}$ ${\llap{-}4}$ ${\llap{-}5}$ ${\llap{-}6}$ ${\llap{-}7}$ ${\llap{-}8}$ ${\llap{-}9}$ ${\llap{-}10}$ ${1}$ ${2}$ ${3}$ ${4}$ ${5}$ ${6}$ ${7}$ ${8}$ ${9}$ ${10}$ ${\llap{-}2}$ ${\llap{-}3}$ ${\llap{-}4}$ ${\llap{-}5}$ ${\llap{-}6}$ ${\llap{-}7}$ ${\llap{-}8}$ ${\llap{-}9}$ ${\llap{-}10}$ $(7, 0)$